已知A=x^2-y^2,B=4xy-y^2,求2A-{B-[A-(2A+B)]}

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已知A=x^2-y^2,B=4xy-y^2,求2A-{B-[A-(2A+B)]}已知A=x^2-y^2,B=4xy-y^2,求2A-{B-[A-(2A+B)]}已知A=x^2-y^2,B=4xy-y^

已知A=x^2-y^2,B=4xy-y^2,求2A-{B-[A-(2A+B)]}
已知A=x^2-y^2,B=4xy-y^2,求2A-{B-[A-(2A+B)]}

已知A=x^2-y^2,B=4xy-y^2,求2A-{B-[A-(2A+B)]}
原式=2A-B+[A-(2A+B)]
=2A-B+A-2A-B
=A-2B
=(x²-y²)-2(4xy-y²)
=x²-y²-8xy+2y²
=x²+y²-8xy

2A-{B-[A-(2A+B)]}
=2A-(2B+A)
=A-2B
代入得 A-2B=x^2-y^2-8xy+2y^2
=x^2+y^2-8xy